title: Survival of Escherichia coli in two sewage treatment plants using UV irradiation and chlorination for disinfection.
abstract: We investigated the survival of Escherichia coli in two STPs utilising UV irradiation (STP-A) or chlorination (STP-B) for disinfection. In all, 370 E. coli strains isolated from raw influent sewage (IS), secondary treated effluent (STE) and effluent after the disinfection processes of both STPs were typed using a high resolution biochemical fingerprinting method and were grouped into common (C-) and single (S-) biochemical phenotypes (BPTs). In STP-A, 83 BPTs comprising 123 isolates were found in IS and STE, of which 7 BPTs survived UV irradiation. Isolates tested from the same sites of STP-B (n = 220) comprised 122 BPTs, however, only two BPTs were found post-chlorination. A representative isolate from each BPT from both STPs was tested for the presence of 11 virulence genes (VGs) associated with uropathogenic (UPEC) or intestinal pathogenic (IPEC) E. coli strains. Strains surviving UV irradiation were distributed among seven phylogenetic groups with five BPTs carrying VGs associated with either UPEC (4 BPTs) or IPEC (1 BPT). In contrast, E. coli strains found in STP-B carried no VGs. Strains from both STPs were resistant to up to 12 out of the 21 antibiotics tested but there was no significant difference between the numbers of antibiotics to which surviving strains were resistant to in these STPs. Our data suggests that some E. coli strains have a better ability to survive STPs utilising chlorination and UV irradiation for disinfection. However, strains that survive UV irradiation are more diverse and may carry more VGs than those surviving SPTs using chlorination.
authors.affiliation: Faculty of Science, Health and Education, University of the Sunshine Coast, Maroochydore DC 4558, Queensland, Australia; Smart Water Research Centre, Griffith University, Gold Coast Campus, Queensland, Australia.
authors.forename: E M
authors.initials: EM
authors.lastname: Anastasi
authors.forename: T D
authors.initials: TD
authors.lastname: Wohlsen
authors.forename: H M
authors.initials: HM
authors.lastname: Stratton
authors.forename: M
authors.initials: M
authors.lastname: Katouli
mesh_terms: D001673:Biodegradation, Environmental / Q000528:radiation effects; D004203:Disinfection; D004352:Drug Resistance, Microbial / Q000528:radiation effects; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology / Q000528:radiation effects*; D054879:Halogenation / Q000528:radiation effects; D050296:Microbial Viability / Q000528:radiation effects*; D012722:Sewage / Q000382:microbiology*; D014466:Ultraviolet Rays; D014774:Virulence / Q000235:genetics / Q000528:radiation effects; D018508:Water Purification
chemical_list: D012722:Sewage
keywords: Chlorination; Disinfection; Escherichia coli; Sewage treatment plant; UV irradiation